<template>
    <el-container>
        <!-- 头部区域 -->
        <el-header>
            <div>
                <img src="../assets/logo.png" alt="">
                <span>电商后台管理系统</span>
            </div>
            <el-button type="info" @click="logout">退出</el-button></el-header>
        <!-- 页面主体区域 -->
        <el-container>
            <!-- 侧边栏 -->
            <el-aside :width="isCollapse ? '64px' : '200px'">
                <!-- 菜单折叠按钮 -->
                <div class="toggle-button" @click="toggleCollapse">
                    |||
                </div>
                <!-- 菜单 -->
                <el-menu background-color="#333744" text-color="#fff" active-text-color="#409eff"
                    unique-opened :collapse="isCollapse" :collapse-transition="false" router :default-active="activePath">
                    <!-- 一级菜单 -->
                    <el-submenu :index="item.id + ''" v-for="item in menulist" :key="item.id">
                        <!-- 一级菜单模版 -->
                        <template slot="title">
                            <!-- 菜单图标 -->
                            <i :class="iconObj[item.id]"></i>
                            <!-- 菜单文本 -->
                            <span>{{item.authName}}</span>
                        </template>
                        <!-- 二级菜单 -->
                        <el-menu-item :index="'/' + subItem.path" v-for="subItem in item.children" :key="subItem.id" @click="saveNavState('/' + subItem.path)">
                            <template slot="title">
                                <!-- 菜单图标 -->
                                <i class="el-icon-menu"></i>
                                <!-- 菜单文本 -->
                                <span>{{subItem.authName}}</span>
                            </template>
                        </el-menu-item>
                    </el-submenu>
                </el-menu>
            </el-aside>
            <!-- 页面内容 -->
            <el-main>
                <!-- 路由占位符 -->
                <router-view></router-view>
            </el-main>
        </el-container>
    </el-container>
</template>

<script>
export default {
    created () {
        this.getMenueList()
        this.activePath = window.sessionStorage.getItem('activePath')
    },
    data () {
        return {
            menulist: [], // 左侧菜单列表
            iconObj: { // 菜单图标对象
                125: 'iconfont icon-users',
                103: 'iconfont icon-tijikongjian',
                101: 'iconfont icon-shangpin',
                102: 'iconfont icon-danju',
                145: 'iconfont icon-baobiao'
            },
            isCollapse: false, // 是否折叠菜单
            activePath: '' // 被激活的菜单链接地址
        }
    },
    methods: {
        logout () {
            // 清空sessionStorage，并跳转到首页
            window.sessionStorage.clear()
            this.$router.push('/login')
        },
        // 获取所有菜单
        async getMenueList () {
            const { data: res } = await this.$http.get('menus')
            if (res.meta.status !== 200) return this.$msg.error(res.meta.msg)
            this.menulist = res.data
        },
        // 点击按钮，切换菜单的折叠与展开
        toggleCollapse () {
            this.isCollapse = !this.isCollapse
        },
        // 保存菜单链接的激活状态
        saveNavState (activePath) {
            window.sessionStorage.setItem('activePath', activePath)
            this.activePath = activePath
        }
    }
}
</script>

<style lang="less" scoped>
.iconfont {
    margin-right: 10px;
}

.el-container {
    height: 100%;
}

.el-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-left: 0;
    background-color: #373d41;
    color: #FFF;
    font-size: 20px;
    > div {
        display: flex;
        align-items: center;
        > span {
            padding-left: 15px;
        }
        > img {
            width: 64px;
            height: 64px;
        }
    }
}

.el-aside {
    background-color: #333744;
}

.toggle-button {
    color: #FFF;
    text-align: center;
    letter-spacing: 0.2em;
    line-height: 24px;
    font-size: 10px;
    background-color: #4a5064;
    cursor: pointer;
}

.el-menu {
    border-right: none;
}

.el-main {
    background-color: #eaedf1;
}
</style>
